import java.util.Stack;
//最小栈
class MinStack {

    public Stack<Integer> stack;
    public Stack<Integer> minStack;
    public MinStack() {
        stack = new Stack<>();
        minStack = new Stack<>();
    }

    public void push(int val) {
        stack.push(val);
        if(minStack.empty()){
            minStack.push(val);
        } else{
            int peekVal = minStack.peek();
            if(val <= peekVal){
                minStack.push(val);
            }
        }
    }

    public void pop() {
        if(stack.empty()){
            return;
        }

        if(stack.peek().equals(minStack.peek())){
            minStack.pop();
        }
        stack.pop();
    }

    public int top() {
        if(stack.empty()){
            return -1;
        }
        return stack.peek();
    }

    public int getMin() {
        if(minStack.empty()){
            return -1;
        }
        return minStack.peek();
    }
}
